Hollow fiber membrane filters in various containers

ABSTRACT

A water filter cooperable with a water container includes both a carbon composite filter ( 30 ) and a bundle of micro porous hollow fiber membranes ( 5 ) in fluid communication with the carbon composite filter ( 30 ). An influent side of the hollow fiber membrane ( 5 ) is continuously immersed in water whereby air is prevented from being reintroduced to the hollow fiber membrane ( 5 ).

BACKGROUND OF THE INVENTION

The need to treat water in an economical and convenient manner forbiological contamination by people away from home, and as they travel,or simply conducting their daily activities has become more evident.While technology allowing filtration of microorganisms from drinkingwater in a squeezable “sports” bottle is available, a number of seriousinadequacies limit the application of microbial filters in thesebottles. For the removal of protozoan cysts from water, an effectivepore size between 1 and 3 microns in the filtration medium isrecommended, while for retention of bacteria particles an order ofmagnitude smaller must be excluded. Filtration media possessing thecapability to exclude particles in this size range is relatively dense,inhibiting the flow of water through the media as well as the materialto be filtered out. The apparent dilemma in designing small filters thatare effective at removing bacteria in particular, and cysts is that thepressure drop per unit surface area is large while the available surfacearea is small.

One approach to alleviating this restriction is to loosen the pore sizesof the filter to allow particles to be deposited throughout the depth ofa bed of media. As the flow path of the water is designed to betorturous, the hope is that weak surface interactions such as van derWaals forces will trap the particles somewhere along the surfaces of theflow paths before they are flushed from the bed. This technology is lessdesirable from a reliability standpoint than techniques thatmechanically screen the particles from the water. Monolithic filters,such as carbon blocks, employ the depth and tortuous path filtrationmechanism for particles. They must use this method because filtering outmaterial onto the surface of such structures would result in lowcapacities due to the pressure required and the small amount of surfacearea available. Reducing the pore size in these blocks would grosslyenhance fouling, and substantially increase the pressure required toachieve a particular flow rate.

Another approach to providing for more surface area within a smallvolume is to employ hollow fiber membranes as the filtration media forsize exclusion. The large surface to volume ratio of the hollow fibersgreatly increases the area available for contact with the bulk fluidphase. But even with the application of hollow fiber membrane bundles,the pressure drop across a filter capable of being deployed as aportable bottle filter is substantial. For hollow fiber bundles of theapproximate dimensions 7.3 Cm in length and 3 Cm in diameter, such asthat produced by Spectrum Laboratories, the flow rate through the bundleunder pressures capable of being effectively supplied by hand squeezingis fairly low. At an applied pressure of 10 psig, the initial flow ratethrough such a bundle is around 12 to 35 ml per second. Any blockage orother restriction to the flow of water through the membrane bundlesresults in even slower flow rates; possibly low enough to no longer beacceptable in actual usage.

An unfortunate problem in the use of hollow fiber membrane bundles insport bottle applications is that if air accumulates inside the bundlehousing between uses, a large percentage of the bottle squeeze must beused to expel air from the filter. Because the air vents by flowingthrough some of the fiber bundles, while the air is venting the flow ofwater exiting the filter is lessened. Testing has shown that it may takeseveral minutes of continuous flow to fully purge the filter of air. Asthe acceptability of the liquid flow rate is already marginal undernormal use conditions, any reduction in flow results in a significantdecrease in performance. Another problem that may be encountered if airis allowed back into the membrane is with entrapped air causing actualmembrane blockage. The hollow fiber bundle referenced by Shimizu in U.S.Pat. No. 5,681,463 suffers from both problems as water will drain fromthe fiber bundle housing as the bottle is returned to an uprightposition.

BRIEF SUMMARY OF THE INVENTION

The present invention eliminates the problem of reintroduction of airinto the bundle housing between uses preferably by enclosing the axiallyjoined filter elements (the hollow fiber bundle and carbon elements)within an impervious shroud that maintains the water level in contactwith the hollow fibers. Thus, between uses, the water within the hollowfiber housing is not allowed to drain, preventing the accumulation ofadditional air that must be voided for full efficiency. This sameapproach has been employed in other designs disclosed in thisapplication to preclude the water from draining from the hollow fibermembrane filter. A second method that may be used when the water intakeis at the base of the housing and the filter is positioned at the baseof a water bottle or canteen is to employ a one-way valve which will notpermit the water to drain back into the bottle or container.

In an exemplary embodiment of the invention, a water filter iscooperable with a water container. The water filter includes a carboncomposite filter and a bundle of sub-micro porous hollow fiber membranesin fluid communication with the carbon composite filter. The carboncomposite filter and the hollow fiber bundle are arranged in the watercontainer such that untreated water is first treated with the carboncomposite filter and then directed to the hollow fiber bundle. Aninfluent side of the hollow fiber bundle is continuously immersed inwater, whereby air is prevented from being re-introduced to the hollowfiber bundle from outside the water filter between inversions of thewater container or when the water container is upright.

In another exemplary embodiment of the invention, a filtration systemfor filtering water includes a water container and the water filteraccording to the present invention.

In still another exemplary embodiment of the invention, a dual componentwater filter includes a hollow fiber membrane bundle and a screenpre-filter. The hollow fiber membrane bundle and the screen pre-filterare contained within a single housing, wherein the housing retains waterwithin the hollow fiber membrane bundle and the screen pre-filter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sport type bottle top mounting the filter of the presentinvention in a nested arrangement;

FIG. 2 illustrates the filter of the present invention in a tandemend-to-end configuration;

FIG. 3 shows the filter assembly of FIG. 2 incorporating a viricidaldisinfecting injection unit;

FIG. 4 shows a free-standing filter assembly adapted to straw use;

FIG. 5 illustrates the dual element filter of the present inventiondesigned to mount to a specially designed cap for use in conjunctionwith a container such as a bladder or hydration pack that collapses asthe water is removed;

FIG. 6 shows the filter of the present invention adaptable to eithersoft or vented containers and fastened to the base or bottom of thecontainer;

FIG. 7 illustrates a filter design according to the present inventionpositioned within a military canteen;

FIG. 8 shows the filter of the present invention adapted for use instandard 28 mm neck PET bottles;

FIG. 9 illustrates a filter of the present invention that may be used todrink through from a glass or cup or a bottle through a straw;

FIG. 10 illustrates the filter of the present invention adapted for usein a relatively narrow neck bottle similar to the international standard28 mm; and

FIG. 11 shows the filter assembly of the present invention with aminimized length.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the selection of hollow fiber membrane bundle technology overmonolithic block approaches, a major concern is the potential formicrobial break-through or grow-through occurring as increasing volumesof fluid are passed through the monolithic filter. Because of thesurface loading and pressure drop restrictions mentioned above, thesemonoliths must employ larger effective pore sizes than high surface tovolume ratio materials such as the hollow fiber membranes. The potentialfor failure is clearly higher in the carbon block monolithic filterspurported to be designed for microbe removal. Filters of this naturehave mean pore sizes in the neighborhood of 10 microns. The monolithsare often reported to have a capacity of as much as 100 gallons, furtherraising concerns about bacteria and protozoa being washed through thedevice. In contrast, the hollow membrane fibers for bacteria removaltypically have a mean pore size approximating 0.15 microns with a rangebetween 0.02 and 0.4, with actual capacities of 75 or more gallons,depending upon pretreatment and the turbidity of the water.

It is of course important to remove bacteria as well as protozoa. Manywater born diseases, including some of the most serious, are caused bybacteria in the water. Viral diseases are not easily amenable to removalvia filtration, and are normally controlled through the use of chemicaldisinfectants. In employing media with effective pore sizes appropriatefor protozoa and bacteria removal in portable products which do notemploy mechanical pumps, the pressure drop from the container throughthe filter and out to the user will be from 2 psig when first used andapproaches 10 psig, deemed a practical limit of usability for theaverage person after extended use. Antimicrobial filters for use insport bottles typically also incorporate activated carbon for theremoval of specified chemical species from the water. If organized asseparate structures, the tendency of these carbon elements to becomefouled with particulates need not be as great as the element used formicrobial removal even though they act as a pre-filter. To maintain thelowest pressure drop, independent filters should be used that areseparately installed and complement one another. The principal advantageto maintaining separate filter elements with differing useful lives isthat each can be replaced independently, depending upon need. This alsopermits the user to revert to a single filter if the need for dualtreatment is not required. Thus, both convenience and economy aregained.

A superior approach permitting the very effective removal of bacteria,as well as protozoa, while retaining the ability to independentlyintegrate a carbon composite, or other filter, and without the reductionin flow rate resulting from air blocking the passage of water, has beendeveloped according to the present invention. The present invention asshown in FIGS. 1-11 extends the life and use of the biological filterelement relative to that of the noted Shimizu patent, by utilizing alarger bundled Hollow Fiber Membrane (HFM)—monolithic carbon elementwhich extends below the neck of the bottle. While the membrane bundlemay only be two-three inches in length and one inch in diameter, as muchas one and one-half square foot of membrane area exists. Thus, while theeffective pore size is between 0.02-0.4 micron, with 0.05-0.2 preferred,pressure drop remains around 10 psig, or less. The filter assemblyincludes a complementing high performance carbon composite element withan average pore size between 10-50 microns, with a preferred porosity of20 microns capable of removing greater than 80% of the chlorine andgreater than 90% of lead at a flow rate of 10 ml/sec. Thus, by combiningthe HFM with the carbon composite filter, protozoa, bacteria, lead,chlorine, taste and odor are removed. Other selected metals and chemicalcontaminants are likewise reduced. The pre-filtration of fineparticulate matter can be enhanced by increasing the wall thickness ofthe carbon composite pre-filter. Under turbid conditions it is alsodesirable to add a third element, a screen pre-filter or other type ofparticulate filter which can be one of several different designsincluding a thin wall ceramic or fiber depth filter. The screen,possessing openings of approximately 10 microns, has been found to besatisfactory as it is cleanable, yet very light weight, and occupies theleast amount of space, which in a portable product is at a premium.Another example to basically provide the same general performance isshown in FIG. 2. The component filters are shown stacked, or in tandem,as frequently referred to. The filters in FIG. 1 are nested, makinginterchange somewhat easier while providing minimum pressure whileallowing larger and higher capacity carbon composite filters to beintegrated. The advantage of the tandem design is the smaller totaldiameter and thus the ability to fit into a substantially smaller neckbottle. Both designs may include a third pre-filter screening element.

Neither filter design is self-venting, thus it is necessary toincorporate a vent with a one-way valve to permit the bottle tore-inflate after taking filtered water from the bottle. Drinking istypically accomplished by opening the valve at the top of the bottle,placing the push-pull mouth piece into ones mouth and squeezing thebottle. The squeezing force may be enhanced by sucking on the mouthpieceor “straw” at the same time. By integrating the air relief valve intothe bottle rather than the filter venting, it is not necessary for theHFM to evacuate the water held within the membrane, thus materiallyenhancing ease of use and eliminating the potential for an air blockage.There is also an advantage to not incorporating the relief valve withinthe filter, as it would be a potential point of leakage andcontamination. A Silicon umbrella relief valve, with a cracking pressurebetween 0.5-3 psig, is mounted within a recess formed into the bottle,protecting the valve from external contact. This is a unique approach tomaintaining the rapid flow of water without the back flushing of eitherfilter occurring. Optionally, the air relief valve may also be installedwithin the bottle top itself which supports the filter in mostinstances. It is further recognized that there are three distinctclasses of biological contamination: protozoa cysts, bacteria, andvirus. Protozoa are typically larger than 3 microns; bacteria are, forthe most part, larger than 0.3 microns, both of which may be filteredout. The third form of biological contamination found in nature consistsof virus, which must be chemically devitalized, as they are too small tobe filtered out by mechanical means that would be usable in a portablefilter bottle product. In the instances of natural disaster, as well asin the developing world, viral pestilence in the only available watercan represent life threatening problems. Thus, it is desirable for aproduct to be able to be adapted to all biological problems andsituations and to the degree possible provide a means of viraldevitalization when necessary. With the proposed products the treatmentfor virus would be done by chemical means through the addition ofchlorine or other water disinfectant.

To this end, a third and optional component injects a disinfectingchemical such as a modified chlorine dioxide solution, or otheravailable disinfectant. In operation, the chemical injecting element isaffixed to the base of the housing containing the carbon compositefilter and the 0.2-micron hollow fiber membrane element. Functionally,each time the filter assembly is removed from the bottle the chemicalinjection mechanism charges. After the bottle is filled with water, thefilter assembly is reinserted. As the filter assembly is threaded ontothe bottle, a precise quantity of the chosen disinfectant is meteredinto the water. The disinfection chemical devitalizes the viralcontaminants in a specified time period, during which the user must waitprior to drawing water from the purifying unit. Alternatively, the usermay make use of an effective chlorine based tablet or other suchdisinfecting product and administer the same to the water manually,placing the chemical element into the bottle following themanufacturer's directions.

The Hollow Fiber Membrane for removal of Protozoa Cyst and Bacteria fromwater combined with a pre-filter also has wide application for use withcanteens as well as collapsing bag type containers. Applications of thisnature extend to gravity feed water bags. In the area that wouldnormally sustain the pull push segment of the valve, the pull pushportion is adaptable to fasten to a tube or hose which in turn can beused to fill a second container. The bag with the raw water containingthe filter is typically hung upside down allowing the water to drainthrough the filter into the second container. Applications of thisnature rely primarily upon gravity, or a combination of gravity andsiphon action, to draw the water through the filtration elements.Typically, the container of water is not squeezed or otherwisepressurized to effect water transfer. This is similar to the filterarrangement used in conjunction with a 2 to 5 gal. cooler or crock typebottle. The filter once again is used in the inverted mode with flowcontrolled by means of the water level rising within the receivingcontainer (crock) until the air supply leading back into the containerby means of a vent tube is closed off.

For the various applications, typically the secondary filter is a housedHFM bundle to which a carbon composite primary filter is attached. Acarbon composite block type filter functions as the primary filterproviding selected chemical and heavy metal removal while at the sametime performing a pre-filtration function removing all but the finesediment particles. Alternately to the carbon block, a non-woven carboncloth depth filter or fine mesh screen of approximately 10-micron may beused for turbidity reduction. By so doing the size and weight isreduced, but at a loss of performance, compared with the monolithiccarbon block composite filter. Regardless of the primary filter elementused, all elements are independently replaceable. The design can besuitable for neck diameters above 35 mm.

The monolithic carbon composite filter is typically of a radial flownature and nominally of 20-micron pore size. Preferably, the compositematerial consists of activated carbon, binder and may contain zeolyte,ion exchange materials and polymer extractive material as well. Thecarbon composite filter will remove greater than 90% of lead and mercurythat may be present, as well as 80% or greater of chlorine to a minimumof 70%, taste and odor toward the end of the useful life of the filterat 20 gal with a flow rate of 10 ml per second. The chlorine capacity ofthe primary filter is advantageous when chlorine is used to treat forvirus. The hollow fiber filter may be as small as 0.1˜0.3 micron andreject particles from 0.05˜0.07 micron as a result of the wall thicknessof the membrane. A minimum three-log reduction of Protozoa and 6-logreduction of bacteria is achieved over the life of the filter. Theso-constructed filter removes protozoa and bacteria to levels asrequired by Government standards for a treatment device of this nature,99.9999% for bacteria and 99.9% for protozoa The filter is capable oftreating from 20 to 100 gallons of water with a pressure drop across thetreatment system of not more than 10 psi with an average turbidityfactor of less than 1 NTU (nephelometric turbidity units). Filter Lifeis determined when water can no longer be passed through the filter.This preferred combination of the primary carbon composite filter andhollow fiber membrane secondary filter has met the testing requirementsof the EPA protocol.

Is important to recognize that the functions provided by the subjectinvention serve the same useful purposes in various size bottles orcontainers. Typically, the neck size of the bottle would range from 28mm through 63 mm in nominal diameters. This provides a significantchallenge as the larger the components the more adaptable they becomeand easier to meet the performance requirements while retaining a highdegree of utility for the product. The larger 63 mm neck offers theopportunity to nest the filter components; the hollow fiber membranewithin a larger diameter carbon composite filter. The 53 mm diameterneck size bottle is better served by placing the individual filtercomponents in tandem whereas bottles with a neck diameter of from 35 mmto 28 mm are easier to produce using an axial flow carbon elementfeeding into the H F M housing with radial flow into the actual membranestructures. The carbon element used in the smaller neck size may be thecarbon composite molded filter element or a filter constructed fromcarbonized nonwoven materials.

Due to the variation in container neck size and the mode (attitude) thebottle is in when used, a variety of designs have been created toevacuate most all the water from the container, as used. Typically whenapplied to a sport type bottle, the bottle is elevated or tipped up todrink causing the water to accumulate at the top rather than the bottomof the bottle. In order to be able to remove, by drinking, most of thewater in the bottle through the filter, an annulus reservoir is usedwhich takes the water from the bottle cap or top of the bottle anddistribute the water to the filtration elements. The filter annulusreservoir also maintains the level water in contact with the hollowfiber membrane element to preclude the draining of the element when notin use. An annulus system of this nature is used with sufficiently widebottlenecks to permit its adaptation, typically 53 to 63 mm neck bottlesalthough it may be used with smaller neck bottles into the range of 38mm diameter neck diameters. The annulus reservoir is a separateclosed-end plastic tube which threads onto the cap with water entryports just below the threaded section. The annulus formed between thefilter elements and the annulus reservoir housing is relatively small,approximately 0.020-0.100 of an inch.

When dealing with smaller bottle openings which require smaller filterelements, it has been found desirable to use a single housing toencapsulate both the hollow fiber membrane as well as the carbonfiltration element, should a carbon filtration element be desired.Rather than to provide a separate filter annulus reservoir, it has beenfound desirable to simply mold or cut longitudinal grooves from the baseof the single filter housing to within approximately three-quarters ofan inch from the top of the housing. The top of the housing is thesection within which the hollow fiber membranes are bonded and to whichthe fitting to the bottle top is incorporated. Access holes at the baseof the longitudinal grooves permit the water to flow into the innerfiltration area of the housing. From the base of the housing to withinapproximately {fraction (1/8)} of an inch from the top end of thelongitudinal grooves, a plastic sleeve is used to seal the groovesturning them into water feed channel. Thus, the same features areachieved with a much smaller neck size as found in the larger diameterfilter assembles using separate annulus reservoir housings.

There are also bottles, or containers, whose preferred drinkingorientation is in the vertical upright plane. To accommodate thisposition for the larger diameter bottles, the use of the annulusreservoir is reversed for water pick-up which in turn feeds a secondaryupright annulus maintaining the water level to the filter elementsprecluding the draining of the hollow fiber membrane and the intrusionof air into this filter element.

When it is desirable to drink from the container in the vertical uprightplane, yet mount the filter to either the top of the container directlyor position the filtration unit through the use of a flange resting uponthe top surface of the neck of the bottle which becomes operativelyconnected to the bottle top, a water intake tube is used to feed waterinto the filtration elements. The intake tube maybe used to either feedthe water into a reservoir annulus for feeding into a radial flow carboncomposite filter, or directly into an axial flow carbon filtrationelement. In either case it is necessary to employ a valve to retain allwater within the filtration elements to preclude draining of water fromthe filtration elements back into the bottle. Several types of valvesmay be used for this purpose but a simple duckbill valve is both simpleand reliable.

The present-day military canteen offers a significant challenge. Amilitary canteen is best served by a filtration assembly that can removebacteria, protozoa, and chlorine, as a minimum. The purpose of thechlorine is to devitalize virus that may be present. And effectivecarbon composite filter will remove the taste and the odor of thechlorine rendering the water palatable to the user. It is highlydesirable to be able to remove a host of other chemical contaminants, aswell. While potentially possible, it is problematic due to the sizeconstraints imposed by the canteen and the neck size of the canteen. Asthe canteen must be available for hydration regardless of whether theuser is wearing a gas mask, or the access to the canteen is restrictedand thus a drinking tube is used, or for unrestricted use water may bedrawn from the canteen by means of a straw. Thus, both a drinking strawas well as the fitting for a drinking tube are desirable. A dual-purposetop has been developed that integrates the multipurpose filtration unitthat may be easily used in either mode. When not used the two availabledrinking outlets are independently sealed for cleanliness. The top alsocontains a reservoir for filtered water that may feed either of the twodrinking outlets as well as an air relief valve, and an orientationnotch to radially position the filtration unit. The filtration unithousing contains a longitudinal disposed air relief tube extending fromthe air relief valve chamber to the base of the filtration unit.However, the relief tube may terminate at any point along the housingsuitable for releasing the air back into the canteen. The housing alsocontains the hollow fiber membrane biological filter, a filterseparator, and the carbon composite filter made up of either carbonizednonwoven cloth, or a monolithic carbon block element.

The carbon filter choice in a unit of this type is challenging, both toremove the potential chlorine loading the filter may be subject to, aswell as to provide a relatively low pressure drop across the filter toprovide at the optimum, a flow of 10 ml/sec with a force of 2 psig. Thisforce can be extended upward to approximately 10 psig. Due to thediameter constraints the simplest design uses the carbon filter elementsin an axial flow configuration.

One alternative to enhance the carbon element is to use an externalcarbon wrap over the housing operating in a radial flow mode. The waterwould feed from the external surface of the carbon element throughlouver openings in the HFM housing and hence feed by means of a tube tothe distribution chamber within the cap. This design can be particularlyattractive for military use where the maximum practical size carbonelement may be desirous to employ.

FIG. 1 shows a sport type bottle top 1 with valve 3, which mounts twoindependent filters 4 and 5. As shown in FIG. 1, an inner hollow fibermembrane (HFM) filter 5 is attached to the bottle top 1 by means of afriction or threaded fit to the inner upper diameter of the filtermounting ring 9, which is a component of and extends down from the top.The placement of the HFM filter 5 into the mounting ring 9 compressesthe “0” ring seal. In a similar manner the primary filter 4, consistingof a monolithic carbon composite mixture, is affixed by means of athreaded top adapter 10 to the threaded cap mount 9. The compositefilter 4 is cylindrical in shape and is mounted to the top threadedadapter 10 and the bottom base 11 by means of a simple adhesive yetwater tight bond. The HEM housing 6 is retained in position relative tomounting boss 9 with the axial loading exerted by the porous springpressure cup 17. A shroud housing 15 is used to allow evacuation of mostof the water within the bottle. The water entry port 12 is indicatedfrom which water flows into the distributing channel 13 prior to passingsequentially through the filter elements 4 and into the secondarytreated water reservoir 14 prior to entering at the base of the membranefilters 5, hence to exit fully treated through the valve 3. A one-wayvalve to permit the bottle to re-inflate after water has been removed isshown at 2. Seals to prevent leakage are represented by 8 and 8A. Thehollow fiber membrane bundle housing 6 is retained within the housing bythe potting compound 7. The optional pre-filter screen 18 ofapproximately 10-micron pore size is used to remove excess turbidity orparticulate matter. The screen may be easily removed and cleaned bybrushing. A pressure cap 17 fits to the base of the hollow fibermembrane housing 6 and retains the hollow fiber membrane filter 5 in itsposition with the sealing surfaces 8 and 8A in conjunction with thebottle top 1.

FIG. 2 shows essentially the same components arranged in tandem ratherthan in a nested orientation. This configuration is useful when thecontainer or bottle neck diameter is limited. A section of a typicalsport bottle cap is shown 1, containing a valve 3, and an integralfilter mounting ring boss 22. While there are many ways that the filterassembly contained within the outer shell 15 can be affixed, for thepurpose of illustration, a threaded connection 23 is shown. The primarycarbon composite filter 30 is centered by the centering taper 36components of the outer shell housing 15. The secondary hollow fibermembrane filter 5 is positioned above the primary carbon filter 30, anda seal between filters is formed by means of the filter adapter 34,which is a separate component integrating the filter element 30 with thehollow fiber membrane assembly 5. Axial loading to affect a seal isapplied by means of the threaded tensile connection made between thetop-mounting ring 22 and the outer shell 15 as the two components arethreaded together compressing the “O” ring seal 8 while retaining thefilter assemblies and sealing surfaces together. Water enters the shroudthrough entry port 12, and passes outside of the HFM assembly housing 6by means of the water distribution channel 13. The water is then drawn,or is forced through the sidewalls of the carbon composite filter 30.The flow of water through the filter is a result of pressure beingexerted through squeezing the plastic bottle or a sucking pressureexerted upon the valve 3. The treated water from the primary filter 30then passes into the water-distribution reservoir 29, distributing thewater to the full bundle of hollow fiber membranes 5 for finalbiological treatment. The water exits through the membranes held inplace by potting compound 7, and hence through the valve 3 exiting atthe top of the valve 19.

FIG. 3 shows the addition of the viricidal disinfecting injection unit.This unit is designed to affix to the base of the existing filter systemhousing 15 by means of a dovetail mechanical connection 37, althoughthere are many means of connecting the components such as by threads, asimple friction fit, etc. It must be recognized that while this elementbecomes an integral element in the purification system, it isnevertheless an optional component added for the purpose of eliminatinga viral organism and simplifying the addition of a disinfecting chemicalsuch as chlorine. The elements of this unit are: a housing 38, whichcontains a reservoir with a sufficient chemical capacity for numerousapplications, and the individual dose injection mechanism. As shown inFIG. 3, integrated within the housing is the reservoir 40, a valvedchemical entry port 41, a precision charge reservoir 42 which is thedosage, a sealed piston 44, and attached actuator 46. When the filterassembly system is placed into the bottle and the top threaded closed,the actuator is thrust upward by contact with the base of the bottle. Asthe piston 44, is moved upward it forces the viricide/biocide from thecharge reservoir 42, through the valved injection port 39, and into thewater-containing bottle. When the filter system assembly is removed froma bottle to fill the bottle with water, the return spring 45 forces theactuator 46 and piston 44 down creating a void and suction causing thevalved entry port 41 to open and refill the charge reservoir 42 from thechemical reservoir 40.

FIG. 4 is yet a different approach using a freestanding carbon compositehollow fiber filter assembly which may be used either in a sport typebottle adapted to straw use, or as a personal product used independentlywhile traveling. In FIG. 4, a unique approach has been taken to assurethat the hollow fiber membrane filter is always submerged in water topreclude the possibility of air blockage resulting from water drainingfrom the filter. The subject drawing consists of and outer. housing 1,which forms the intake annulus 49. At the base of the annulus is thewater entry port 48 which delivers water on demand to the secondaryintake port 51 which in turn provides the water for the secondary feedannulus 50. Water from the secondary annulus 50 transfers radially intothe carbon composite filter 35. The water then flows axially through theadapter connecting the dual filter elements 55, and into the H F Mhousing 2. Within the housing the water enters the sub micron hollowfiber membranes 26, and flows into the straw connection 54, and to theuser. The HFM filter 26 with “O” ring seal 52 is attached by means of afriction fit to adapter 55, which in turn forms a friction fit with thecarbon composite element 35. The filters are then inserted within theinner housing 51 which in-turn is threaded 23 into outer housing 1. Athreading key 23 is molded into the base of inner housing 51 to providea means to exert threading force.

FIG. 5 shows a dual element filter designed to mount to a speciallydesigned cap which may be used in conjunction with a container such as abladder or hydration pack which collapses as the water is removed, or toa more rigid bottle with a built in pressure relief valve. In thisdesign, the same basic hollow fiber membrane is used as the biologicalsecondary filter. The primary filter consists of a carbon compositemolded block, or one or more carbon fiber discs providing thepre-filtration and chlorine removal capability. A separator supportprovides the support surface that the post filter 42 nests against. Thecarbon filtration elements 38 are directly below the post filter 42, andsupported in place by pre-filter 41. The pre-filter support 39 supportsthe post and pre-filter as well as the carbon elements. The post andpre-filters consist of nonwoven fine mesh materials. Below thepre-filter support 39, a duckbill one-way valve is used to retain waterpreviously drawn into the filter elements in order to prevent air fromentering the H F M filter during periods of inactivity. In thisparticular design, the filtration elements are not interchangeable,although the housing 31 could be made into two sections that threadtogether in the area of the separator support 37. When constructed intosections, the filter elements could be independently changed. At thebase of the filter housing 31, a duckbill valve 32 is assembled at thepoint the housing tapers to a hose, or tube, connection. A pick-up tube40 is attached to the tube connection and extends to the base of thecontainer for maximum water removal. The threaded connection 34 permitsthe adaptation of either a drinking tube or push pull drinking valveadding to the flexibility of the design. For assembly, the outer housing31 is used to sequentially inset the duckbill valve 32, the base ofwhich fits within a molded groove, followed by stacking the prefiltersupport 39, which nests upon the shoulder formed at the base of housing31, upon which the prefilter 41, carbon elements 38, and post filter 42are placed. The separator support 37 is then assembled, and the HFMhousing 2 is inserted. HFM housing 2 is used to compress the previouslyinserted elements and is held in place by compression ring 2A

FIG. 6 is a design adaptable to either soft or vented containers towhich the filter assembly is fastened to the base or bottom of thecontainer. An advantage of such an arrangement is to provide the headpressure exerted by the fluid within the container to aid in deliveringwater through the filter to the user. This design is only slightlymodified from the preceding designs in that the water entry ports 56 areup at the neck of the container rather than at the base of the filter.Also, the threaded water housing 27 provides a raw water reservoir 28within the annulus formed. The single porous spacer 55, which is asnap-in friction fit element, retains the nonwoven pre-filter 52, whichin turn, is followed by the carbon support porous spacer 62A supportingthe carbon composite or carbon fiber disc filters 57, which in turn areseparated from the hollow fiber membrane bundle 26 by the support porousspacer 62B, which is a molded in fixed component of the housing 31. Ahose fitting 45 is fitted to the container top 43 for use with adrinking tube, however a quick change connection, or shut off type valvemay be use if the container is to be hung filled with raw water to befiltered. In applications of this nature, over time, the treated wateris fed into a second treated water container positioned below the rawwater container with filter.

FIG. 7 represents a new filter design positioned within a militarycanteen from which water may be accessed by two means. The water may beremoved by sucking on a straw or by means of a drinking tube affixed tothe gas mask adapter. While similar to the preceding designs, there aresome major differences that are worth noting which will become apparentas the design is reviewed. The hollow fiber membrane and the carboncomposite filter are contained within housing 69 and supported by meansof the flange 63 at the top of the housing which fits onto the neck ofthe canteen and is operatively connected to the canteen top. The flange63 provides the seal as well as an orientation notch which positions thefilter housing radially. The radial positioning places the air relieftube 67 port opposite the air relief valve 65. The air relief valve iscontained within the side of the duel flip top 68. The canteen topincorporates both a separate gas mask adapter and drinking straw, whichare both maintained in a covered and protected nests ready for use. Whenflip top lid 68A is opened, the straw 63A flips up, and when the fliptop 68A is closed, the straw is retained within the straw receptacle63B. The gas mask adapter 64 is accessed in a similar manner by openingflip top lid 68B. The air relief valve 65 integrates with the air reliefpassage 67 which is a thin covered tube formed into the filter housing69 which feeds air back into the canteen as water is displaced. Thegroove formed in the housing 69 is turned into a tube by means of a thinMylar sheet, or similar material 68 which is wrapped or shrunk aroundthe filter housing 69. Due to space limitations, the outer housingdirectly contains the hollow fiber membrane 26 as well as the integralmolded in separator 62 to support the carbon composite elements 57,which may be either carbon composite block, GAC, or carbon compositecloth. A porous carbon element retainer 70, while supporting the carbonelement 57, also provides an incoming water distributional channel tothe carbon elements. The base retainer rests upon and is supported bybase plate 21. A unidirectional valve 24 is assembled and secured withina nest to the base plate 21 water entry port to retain water within thefilter assembly to reduce the chance of air blockage caused by waterhaving been drawn into the HFM element and consequently draining backinto the canteen during the time the filter was not in use. The baseplate 21 is threaded onto the housing 69. A water pick-up tube 59extends to the bottom of the canteen.

FIG. 8 is the design of the combined carbon composite and hollow fibermembrane filter for use in the standard 28 mm neck P E T bottles whichare used for water and soft drinks. In this particular design, thefilter housing 71 is secured in place, or retained, by a friction fit orthreaded connection to the cylindrical boss on the bottle cap with pushpull valve 78, which is an industrial standard. The user when refillingthis bottle does not touch the filter assembly which is in contact withthe water, thus eliminating this potential for contamination. A seriesof longitudinal grooves 73 molded into the filter housing 71 are themajor differences in actual filter design and construction. Thesegrooves which extend from the base of the filter housing to withinapproximately three quarters of an inch of the top of the housing areclosed to within ⅛ in of the top of the grooves to form tubes 68 whichfunction as water flow channels. The grooves are closed byshrink-wrapping a plastic sleeve 68 around the filter housing 71converting the grooves into tubes, or channels. Water intake ports 24are placed in the top of the water tubes. Water outlet ports 75 into thefilter area are molded into the base of the filter housing 71 and closedto the external surfaces by means of the base plug 76, which is retainedin place by either a snap fit into a groove within the base of thehousing 71, or by the shrink wrapped film. A single monolithic carbonfilter element 77 is incorporated within the design, although carbonfabric disks or granulated activated carbon could also be used. As thewater inlet 24 is near the top of the HFM filter, water cannot drainfrom the filter causing air blockage or requiring water to be drawn backthrough the filter with each use.

FIG. 9 represents a similar size filter employing essentially the samehollow fiber membrane bundle 26 and carbon composite filter element 77.This particular design is for use by the traveler and may be used todrink through from a glass or cup or a bottle through a straw providedneither the cap or straw cap interface on the bottle is airtight. Thefilter housing 80 has a straw adapter housing 82 permanently affixed bymechanical, adhesive, welding, or other means. A tube which functions asa straw 83 is held in place in the adapter housing receptacle by meansof a friction fit. The water is drawn through the porous water intakebase cap 79, which also retains the carbon filter element 77. The basecap 79 contains a 0.10″ ring which effects a snap retainer into a matinggroove within the housing 80. It is desirable to add a check valve 81which nests on top of spacer 62A to prevent water from draining from thehollow fiber membrane filter element 26. The valve 81 is positionedbetween porous spacer 62A and porous spacer 62B.

FIG. 10 is again for use in a relatively narrow neck bottle similar tothe International Standard 28 mm. This particular filter is similar tothe filter described in FIG. 8 with the exception that it utilizes aflange. The flange rests upon the top of the bottle neck and isoperatively connected with the bottle and the top when the top isthreaded into position. This design is to be used with a top containinga valve, be it a pull push type or straw that can be pinched closed. Thebottle must be either collapsing or contain a re-inflation valve. Thefiltration assembly containing a carbon composite element 57 and thehollow fiber membrane filter 26 is assembled within the inner housing94. The carbon element is retained in place by press fit lock ring 69and the porous separator 70. This assembly is placed within the outerhousing 93 and welded to the outer housing 93. The bottle mountingflange 68 is a component of the outer housing 93. The top of the flangeis open to permit water exit over area 25. The end of the outer housingis sealed by base plug 70 which snaps into outer housing 93.

FIG. 11 presents a departure from the other designs permitting a minimumlength to be obtained with significantly increased capacity to removechlorine and other selected elements with a minor increase in diameter.The hollow fiber biological membrane 89 is contained within a housingwith louver type openings which cover most of the length of the H F Mfilter element 89, providing water access. The louvered housing 86 iscovered by an extruded carbon composite closed-end sleeve. The tube orstraw adapter 84 is shown connecting to the filter housing 87 above theadhesive seal 92 and may be either welded or threaded in place.Following the assembly of the straw adapter 84, the carbon element 85 isbonded in place to the base of the adapter 84. The hose adapter 84 isdesigned to support the delivery tube 90 at right angles to the axis ofthe filter assembly allowing the filter assembly to rest upon the bottomof the canteen in a horizontal plane while the delivery tube extendsvertically upward to the canteen cap. A feature of the hose adapter 84is the relief at the top of the adapter to permit the delivery tube tobe bent 90 degrees to facilitate placement within a relatively smalldiameter canteen opening. For filter removal, a line or lanyard 91 isattached to the delivery tube 90 and to the end of the hose adapter 84.When the tube 90 is pulled from the hose adapter 84, the removal line 91allows the filter assembly to assume a vertical orientation for easyremoval from the relatively narrow neck canteen as the tube with chiefattached filter are withdrawn.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. A water filter cooperable with a water container, the water filtercomprising: a carbon composite filter; and a bundle of sub-micro poroushollow fiber membranes in fluid communication with said carbon compositefilter, wherein the carbon composite filter and the hollow fiber bundleare arranged in the water container such that untreated water is firsttreated with the carbon composite filter and then directed to the hollowfiber bundle, and wherein an influent side of the hollow fiber bundle iscontinuously immersed in water whereby air is prevented from beingre-introduced to the hollow fiber bundle from outside the water filterbetween inversions of the water container or when the water container isupright.
 2. A water filter according to claim 1, further comprising anouter shroud housing the carbon composite filter and the hollow fiberbundle, the outer shroud having at least one water inlet port foruntreated water and being formed of a material substantially imperviousto water.
 3. A water filter according to claim 2, wherein the shroud isconfigured to permit substantially total removal of water from the watercontainer while retaining the water within the filtration elements.
 4. Awater filter according to claim 2, wherein the outer shroud is formed inmultiple disassemblable pieces.
 5. A water filter according to claim 2,wherein the outer shroud comprises exterior longitudinal grooves, andwherein the outer shroud is covered with a sheet of a plastic materialdefining water delivery tubes with said grooves, the water deliverytubes maintaining a water level within the outer shroud to precludewater from draining from the water filter and prevent entry of airtherein.
 6. A water filter according to claim 5, wherein one of thewater delivery tubes extends a full length of the water filter and issealed from water, the one tube serving as an air relief port throughthe water container.
 7. A water filter according to claim 1, wherein thecarbon composite filter and the hollow fiber bundle are arranged in anesting configuration.
 8. A water filter according to claim 1, whereinthe hollow fiber bundle comprises a pore size between 0.1-0.3 micron. 9.A water filter according to claim 1, wherein the carbon composite filteris a composite monolithic block in a closed end cylinder configurationcomprising activated carbon and binder.
 10. A water filter according toclaim 9, wherein the carbon composite filter further comprises zeolyte,ion exchange materials and polymer extractive material.
 11. A waterfilter according to claim 9, wherein the carbon composite filter has anouter surface area of at least 9 in².
 12. A water filter according toclaim 1, wherein the carbon composite filter and the hollow fiber bundleare independently interchangeable.
 13. A water filter according to claim1, wherein the hollow fiber bundle is between 2-3 inches in length andat least 1 inch in diameter containing at least about one square foot ofavailable membrane treatment surface area.
 14. A water filter accordingto claim 1, wherein the carbon composite filter and the hollow fiberbundle are arranged end to end.
 15. A water filter according to claim14, further comprising a single mount coupleable with the watercontainer.
 16. A water filter according to claim 1, further comprising apre-filter disposed upstream of the carbon composite filter.
 17. A waterfilter according to claim 16, wherein the pre-filter comprises woven andnon-woven material or screen with a pore size of about 10 microns.
 18. Awater filter according to claim 17, wherein the pre-filter contains adensified carbon composite filter element with a pore size between about10-20 microns.
 19. A water filter according to claim 1, furthercomprising a chemical disinfecting automatic injector in fluidcommunication with the carbon composite filter and the hollow fiberbundle, the chemical disinfecting automatic injector including achemical reservoir and a release mechanism.
 20. A water filter accordingto claim 19, wherein the chemical disinfecting automatic injector is anindependent component capable of being selectively attached and removed.21. A water filter according to claim 20, wherein the chemical reservoiris refillable.
 22. A water filter according to claim 20, wherein thechemical reservoir is permanently sealed.
 23. A water filter accordingto claim 19, wherein the chemical reservoir is sized to contain multiplechemical doses comprising one of chlorine, iodine and derivativesthereof.
 24. A water filter according to claim 19, wherein the releasemechanism releases a predetermined chemical dosage.
 25. A water filteraccording to claim 24, wherein the predetermined chemical dosage isselectively adjustable.
 26. A water filter according to claim 24,wherein the release mechanism is engageable with the water container toeffect release of the predetermined chemical dosage.
 27. A filtrationsystem for filtering water, the filtration system comprising: a watercontainer; and a water filter cooperable with the water container, thewater filter including: a carbon composite filter, and a bundle of microporous hollow fiber membranes in fluid communication with said carboncomposite filter, wherein the carbon composite filter and the hollowfiber bundle are arranged in the water container such that untreatedwater is first treated with the carbon composite filter and thendirected to the hollow fiber bundle, and wherein an influent side of thehollow fiber bundle is continuously immersed in water whereby air isprevented from being re-introduced to the hollow fiber bundle fromoutside the water filter between inversions of the water container orwhen the water container is upright.
 28. A filtration system accordingto claim 27, wherein the water container comprises a bottle and a bottletop, and wherein the water filter is operatively connectable between thebottle and the bottle top, and wherein the water filter extends into thebottle.
 29. A filtration system according to claim 28, wherein thebottle top comprises a removable valve assembly.
 30. A filtration systemaccording to claim 27, wherein the water container comprises a bottlehaving an air relief valve, permitting water to be pressured into andthrough both the carbon composite filter and the hollow fiber bundle.31. A filtration system according to claim 30, which utilizes anumbrella type silicon valve with a cracking pressure of between 0.5 and3 psig depending upon application and container resilience.
 32. Afiltration system according to claim 27, wherein the carbon compositefilter and the hollow fiber bundle are arranged end to end, and whereinthe water filter comprises a single mount coupleable with the watercontainer.
 33. A filtration system according to claim 27, wherein thewater container comprises a bottle having a neck, and wherein the waterfilter extends into the bottle entirely below the neck.
 34. A filtrationsystem according to claim 27, wherein the water container comprises abottle and a bottle top, and wherein the water filter is secured to thebottle top via a secure waterproof connection.
 35. A filtration systemaccording to claim 27, wherein the water container comprises a durableplastic bottle.
 36. A filtration system according to claim 27, whereinthe water container comprises a multi-gallon crock-type container, andwherein the water filter is positioned in a bottom of the crock-typecontainer such that water flows through the water filter by means ofhead pressure or siphon.
 37. A filtration system according to claim 36,wherein the crock-type container is self-venting.
 38. A filtrationsystem according to claim 27, wherein the water container is acollapsible bottle or bladder comprising a water valve, and wherein thewater filter is coupled with the water valve via a drinking tube.
 39. Afiltration system according to claim 38, wherein an adapter of thedrinking tube secures the water filter within a neck of the collapsiblebottle or bladder.
 40. A filtration system according to claim 27,wherein the water container is a bottle having a 28-35 mm neck bottlecap with an air relief valve, and wherein the carbon composite filterand the hollow fiber bundle are mounted in a single housing.
 41. Afiltration system according to claim 27, wherein the water filter ismountable inside the water container and further comprises a chemicaldisinfecting automatic injector in fluid communication with the carboncomposite filter and the hollow fiber bundle, the chemical disinfectingautomatic injector including a chemical reservoir and a releasemechanism, wherein the release mechanism is actuated to discharge achemical dosage upon insertion of the water filter in the watercontainer.
 42. A filtration system according to claim 27, wherein thewater container is a canteen.
 43. A dual component water filtercomprising a hollow fiber membrane bundle and a screen pre-filter, thehollow fiber membrane bundle and the screen pre-filter being containedwithin a single housing, wherein the housing retains water within thehollow fiber membrane bundle and the screen pre-filter.
 44. A dualcomponent water filter according to claim 43, wherein the housing isshrink-wrapped with a plastic film.
 45. A dual filter element comprisinga sub-micron internal filter nested within a carbon composite outerfilter shell, the sub-micron internal filter and the carbon compositeouter shell both being of a radial flow design.
 46. A dual filterelement according to claim 45, further comprising a straw extendingsubstantially 90 degrees to an axis of the filter element.
 47. A dualfilter element according to claim 46, wherein the straw is bendable at90 degrees to facilitate placement within a container having an openingdiameter that is sufficiently large to permit insertion of the filterelement axially.
 48. A dual filter element according to claim 46,wherein the filter element is configured for removal from a narrownecked container by means of a lanyard attached to the straw, an end ofthe filter providing for ease of removal upon stripping the straw fromthe filter element.